Background: In December 2019, the discovery of the novel coronavirus was first reported in Wuhan, China, which subsequently and rapidly spread throughout the country and worldwide, resulting in a pandemic.After a year of intense research, our knowledge of the new coronaviruses has gradually improved; however, knowledge regarding the time of their complete clearance from the body and the factors influencing clearance are currently inadequate.
Results: We conducted a retrospective observational study comprising 135 patients above the age of 18 years with a confirmed diagnosis of COVID-19 pneumonia, who were admitted to the Public Health Center of Taizhou Hospital of Zhejiang Province, Zhejiang University from January 23, 2020, to March 11, 2020. The findings regarding the duration of the infection from the time of onset to the time of being asymptomatic (whichever was observed first) indicated that novel coronaviruses were cleared from the respiratory tract in a maximum of 84 days and a minimum of 1 day with a median clearance time (quartile) of 20 (13, 30) days. Moreover, viruses were cleared from the digestive tract in a maximum of 72 days and a minimum of 5 days with a median clearance time (quartile) of 25 (20.75, 31) days. The viral shedding time of SARS in the digestive tract was found to be longer than that in the respiratory tract (p = 0.03). Severe disease (P < 0.001), advanced age (P < 0.001), lymphopenia (P = 0.01) and elevated CRP (P = 0.036) were significantly associated with longer clearance time in the respiratory tract. Gender (P = 0.754), novel coronavirus antibodies (P = 0.75), and antibiotic use (P = 0.093) were not associated with the time span required for the novel coronavirus to be cleared from the respiratory tract.
Conclusions: Independent risk factors for the longer clearance time of novel coronaviruses in the digestive tract versus that in the respiratory tract were compared. Severe disease, advanced age, lymphopenia, and elevated CRP were determined to be factors prolonging the clearance of novel coronaviruses.